I bet if you emailed Rick at MakerGear and told him you wanted an assembled unit upgraded to the V4, he could get you set up with one, or at least give you a better idea of when they might be available.

(He might not always be here to check the forum, but he responds to direct emails very quickly.)

I sent Rick an e-mail with the items that I wanted to order which included an assembled M2 with the all metal V4.

His response: "M2s are currently shipping with the v3b extruder. The v4 is currently only available as an upgrade and it is the PTFE v4. We are not shipping the metal v4 yet. I do not have a date yet for the M2 shipping with a v4."

Maybe they ran into a problem with the all metal version and need more time to work it out.